Floating roof tank gauge



/ Feb. 26, 1952 H. A. QUIST 2,587,526

FLOATING ROOF TANK GAUGE Original Filed Oct. 28, 1947 2 SHEETS-SHEET l IN VEN TOR. HAROLD A. QUIST ATTORNEYS Feb. 26, 1952 QUIST 2,587,526

FLOATING ROOF TANK GAUGE griginal Filed Oct. 28, 1947 2 SHEETSSHEET 2 E i I- I l k/ I so 62 6| INVENTOR. HAROLD A. QUIST mryw/lgkdu ATTORNEYS Patented Feb. 26, 1952 UNITED OFFICE fiar'old A. niistjiiljkton, jif'mi. to su "oiigcompane, Philadelphia, Pa 2. 'eiirporation of New terse? 1 949, Serial No. I03,

'5 claims.

invention relates to apparatus -for fiieas'ili ing the liquid contents of storage tanks "and is particularly adapted for use in measuring the "contents of storage tanks floating reefs.

The present application is adivis'ion of ap'- plica'tion Serial No. 7s2 ,53 4, filedOctober 28, "1947, for Floating Roof Tank Gauge.

The principal object of this invention is "to 'mea'si'l'r'e the Iiquid contents of "floating roof tanks quickly and accurately.

Another object is to provide methods of measurement which are'adaptableto tanks oi anymameter and to eliminate the error caused bytilted 'p'onwons, especiauy in the larger tanks.

The invention involves the accurate measiirement of the contents of a *fioa'ting roof storage tank by determining the liquid contents which support the floating roof 'pont'oon and adding to "that 'quantity the measured liquid volume 'whieh surrounds the peripherybf the "pontoon in ex- :cess'of the first computed amount. The calet'llatio'nof the two quantities, the sum or wriieheomprises the total liqu idcontents of -the"floatingroof tank, is obtained frol'n -di'rect readings and reference to conversion tables calculated for' the individual tank.

:tained in stoiage tanks "01f the "heating reer type has been-extremely 'difiieult -and eresent'eda Wide "rang d variable' faict'ols affecting accuracy Such as temperatures; volatility "of the stored-1i fiid;

fleeting of the 'pohtoen rear use to inh e'nt manufactiiring errors, wind, water, and

other loads; density of the'liqiiid in thetankand 'friction With the Side Wall f the Y1).ech31111131311- sea1 often necessary to conserve the ce'ntents. The problems arising from these 'varialble'conditions have been recognized andd'evices have been proposed to correct the effectsand Iaei' mi t adirec treadingbf the liquid contents in tanks "on indicating seales. Two types 'of-such'fievices,

by the .tiltingof the fidaitihg roof which'wa' not corrected even assuming that the device whs otherwise accurate. Byempm'y'ing the method and ap aratus-outlined hereit is 'p'o'ssib1e to de- 'termine the true depth bf the liquid to within 5% of an inch. I

I-hese'and other objects of this invention as "may appear from this specification 'Will be best i lild'eistbbd fromadescription "df the accompany- (algae-29b in; drawings whichillustrate aprefeire'd embodi- 'm'e'n't thereof and in which:

Figure 1 is an elevation in 'secti'onof the meas- 'uifingdevice. H

Figure 2 is an elevation partly broken away or an ulla'gerod. I

Figure 3'is a plan view "df'the ulla'ge rod, w

Figure '4 is 'a paras-11y prok'en away view if "the valvemember "of the 'ullage "rod.

In gauging the contents 'of stdiage tanks with floating roofs it is necessary to eliminate the errorpr measnreiiient'vvhich is daflsed 'hythe tiltingof the flbatingloofpdntodh. This i's done by either measuring the 'point of average depth of the floating'ljoof above the bottom of the tank, normally at the "center point 'as di'sclose'dfih application Serial No. 7825534 "'oitiihih this is a division, or by averaging-severalwell-spacedread' ing's aboutthe pontoon. Figure 1 shows the application of the principles of these methods of measuring to larger diameter tanks of the 'fl'oating rocif type'wher'e it is not ractic'al "to con- 's'tri'ict overhead suspending devices to mak'e the center bf the roof p'o'ntbbn accessible. an elementary requirement it is still necessary to correct the i eading of the elevatio'n of the roof 'tiente'dn for any tilt. fhas been accomplished by "using two tapes 3U-a'n'd 31 pla'ced diametrically fiidposite to each Other on the' fioating roof pontoon 32. A greater number of readings around the peripheryof the "floating r'o'of may be taken, the two, diametrically opposed, in this pr eferred erfibddimeht being the riiihi'iiiiim to 'ahie'v'e the -'desir'ed result. A plat ferml3 is m'eun-ted above steragewm 34 to enableen observerto read the -e1ei7ati6n o f point 3 6 on =p"o ritool i- 32 'a's indie'ated -at-datum plane 36 011 *the'upp'er-ed'ge of alnmihi-im tube'31.

Diametric'ally a posite from point 35 wher tape 30 is attached to pontoon-'32 asecondtape iil is fastened -to the pontoon at "point 45. This ineasuring tape is "shown as traversing pulleys '46 and "41 to "the 'outsidebf tank 34 wher efitjs dropped downward to a reading station 48. If it isnot desired touse this form of construction, "the platform gevice disclosed above for 'reading "the *firsft tapest inay b'e repeated ea-this side -f *t lie tarik. Fina eerieherai-seam 49 complete the p Macon-structure.

The -615jec't oi the readings taken from the graduated"diametri'eally foppos'it'e tapes 3ll and 31, o r'n 'any reater namber-of such 'capes Spaced yatsiipstamianyequm itscen' r *or n ne'riy, is to :d'e-

the s'tor'ed -Iiqili1'i e tan l)" a tamina average de'pth of' below a level coincident with the center of the lower or submerged face of the roof; that is, the average depth of the liquid below the lower face of the roof, as hereinbefore explained.

Preferably two or more tapes 30, 3! should be located at equal distances from the center of the roof and spaced apart at equal arcuate distances, thus enabling the degree of tilting of the pontoon to be more readily calculated; but this spacing is not essential, since if such variable known distances exist, the degree of tilting of the pontoon is calculable. It is unnecessary to provide more than two diametrically opposite tapes 30, 3|. This will be readily understood on the assumption that the tilting is in the direction of a line connecting the two tapes. But even if the tilting should be in a different direction, the readings on the scales 3'5 form a reliable basis for calculating the average depth of the liquid below a level coincident with the level of the center of the lower face of the pontoon. For example, assuming that the tilting should be, at right angles to a line connecting the two tapes, while the two tapes would give the same scale reading, it will be understood that such reading will indicate the depth of the liquid below said level.

Adjacent point 35, as shown (or point 45) the pontoon is formed with a tubular orifice 10 extending through it from top to bottom into which the liquid in the tank is free to flow to partially fill it. The tube and the tape connecting points are spaced apart in the drawing for clarity, but the closer they are the more accurate the calculated liquid quantity. The ullage rod 40 is lowered therein on guide wires 4! and 42. Mounted on the platform 33 are two self-winding wheels 43 and 44 which respectively keep tape 39 tight for elevation readings at point 35 and raises and lowers the ullage rod ill to take liquid depth reading in gauge tube 38.

a complete and operating appliance. Glass tube 50 is mounted between upper cap 5!, vented by hole H, and lower cap 52 and retained in place by said caps held by the three rods 53, 54 and 55. A handle 55 is attached to a yoke 51 which is coupled to valve member 58 by sliding rods 58 and 59. The top of valve member 60 is faced with a gasket 6| which forms a seal with the opening 62 when the ullage rod is closed. A scale 53 is mounted on the glass tube 59 and is held in position against the glass tube by bent rod 66 and brass wire clips 65.

It then remains. to determine the quantity of liquid which is above the underside of the floating roof pontoon and then to,add this quantity to the already determined volume in the storage tank. The depth to which the pontoon sinks in the stored liquid depends upon many factors, chief of which are original construction details, friction of side seals, external loading and density of the supporting liquid. It will be evident that not all of these factors are constant so that readings must be taken regularly of the depth of the displaced liquid. In the illustrated gauging device this reading is readily obtained by dropping the ullage rod into the gauging tube which is shown in the floating pontoon until the upper bracket 5| rests on the gauging tube. This places the ullage rod in position to measure the liquid above the under side or lower surface of the pontoon. The body of the ullage rod thus suspended, further release of the suspending line will permit the handle 56 to descend, in turn dropping valve member 60 from the opening 62. After a short period of time the line suspending the ullage rod being pulled up, lifts the handle 55 which, in turn, closes the valve member 50 and retains an amount of liquid in the ullage rod equivalent to the depth of liquid which surrounds the pontoon above the under surface. The vent hole H permits the air in the rod to be exhausted allowing the liquid to rise to the true depth. In the case of the larger diameter storage tanks Where the gauging tube is placed near the periphery of the floating pontoon, it is necessary to correct the ullage rod reading in proportion to the difference in reading of the diametrically opposed tapes and thereby determine the average liquid height above the under surface of the pontoon. Reference to a prepared conversion table will correct the ullage rod depth to liquid content measure which can readily be added to the originally obtained quantity and an exact reading of the contents of the tank obtained.

The method and apparatus here disclosed affords an accurate measure of the contents of floating roof tanks. The content of the tank which supports the floating roof pontoon can be mathematically determined very closely and found by entering a prepared volume table with the tape measure reading. The greatest source of error in storage tanks of this type has always been in determining the effect of the floating roof pontoon on the storage liquid. This disclosure affords a method and apparatus which once calculated and volume tables prepared will automatically correct for pontoon tilt, manufacturing irregularities, friction, density of the liquid stored, the eflfect of the elements and other causes which have not been considered prior to this in- Vention.

I claim:

1. A device to measure the liquid contents of a floating roof storage tank comprising in combination, two diametrically opposed tapes adapted to read the height of the floating roof surface in contact with the supporting liquids above the bottom of said tank, pulleys conducting said tapes to convenient reading positions adjacent said tank, a tube open to the liquid of the storage tank in said floating roof proximate one of said two tapes, and an ullage rod for insertion into said tube to determine the depth of the liquid displaced by said floating roof.

2. A liquid measuring device comprising in combination a tank adapted to contain liquid, 2. floatingroof within said tank supported on the surface of the liquid, 2. gauging tube adjacent the perimeter of said roof open to admit the liquid, roof elevation measuring means positioned in spaced relation about the perimeter of said roof, andan ullage rod removably insertable in said gauging tube to determine the liquid displacement of the roof.

3. A liquid measuring device comprising in combination a tank adapted to contain liquid; a floating roof within said tank supported on the surface of the liquid and responsive to elevation changes of said liquid; roof elevation measuring means including a number of graduated tapes oooperating with the perimeter of said roof at spaced intervals adjusted to read the elevation of the liqably insertable in said gauging tube to determine the liquid displacement of the roof.

4. A device to measure the liquid contents of a floating roof storage tank comprising in combination means for measuring the quantity of liquid below the liquid contact surface of said floating roof at selected diametrically opposed points thereon, a gauge tube open to the stored liquid through the floating roof proximate one of said selected points, and an ullage rod insertable in the gauge tube to measure the depth of the liquid displaced in floating said roof at said selected point.

5. A liquid measuring device for tanks having a floating roof within said tank supported on the surface of the liquid comprising a gauging tube in said roof open to the liquid in the tank and positioned adjacent the periphery thereof, a cantilever platform extending from the wall of said tank'over said gauging tube, an ullage rod adapted to be suspended from said cantilever platform and enter said gauging tube to measure the displaced liquid elevation therein, a plurality of graduated tapes attached in spaced relation around the periphery of said floating roof beginning adjacent said gauging tube and extended to convenient reading positions adjacent said tank, the tape adjacent the gauging tube extending to a reading station on said cantilever platform.

HAROLD A. QUIST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,117,185 Lynskey May 10, 1938 2,237,461 Tokeim Apr. 8, 1941 2,486,823 Cramner Nov. 1, 1949 

